Test detects every known human virus from single drop of blood

Researchers have developed a new test that can detect every known human virus that currently or previously infected a person from a single drop of blood.
The method developed by Howard Hughes Medical Institute (HHMI) researchers can test for current and past infections with any known human virus, including HIV and hepatitis C.
The method, called VirScan, is an efficient alternative to existing diagnostics that test for specific viruses one at a time.
With VirScan, scientists can run a single test to determine which viruses have infected an individual, rather than limiting their analysis to particular viruses.
The comprehensive analysis can be performed for about USD 25 per blood sample.

Stephen Elledge, an HHMI investigator at Brigham and Women's Hospital and his colleagues have already used VirScan to screen the blood of 569 people in the US, South Africa, Thailand, and Peru.

VirScan works by screening the blood for antibodies against any of the 206 species of viruses known to infect humans.
The immune system ramps up production of pathogen-specific antibodies when it encounters a virus for the first time, and it can continue to produce those antibodies for years or decades after it clears an infection.
That means VirScan not only identifies viral infections that the immune system is actively fighting, but also provides a history of an individual's past infections.

To develop the new test, Elledge and his colleagues synthesised more than 93,000 short pieces of DNA encoding different segments of viral proteins.
They introduced those pieces of DNA into bacteria-infecting viruses called bacteriophage. Each bacteriophage manufactured one of the protein segments - known as a peptide - and displayed the peptide on its surface.
As a group, the bacteriophage displayed all of the protein sequences found in the more than 1,000 known strains of human viruses.
To perform the VirScan analysis, all of the peptide-displaying bacteriophage are allowed to mingle with a blood sample. Antiviral antibodies in the blood find and bind to their target epitopes within the displayed peptides.

The scientists then retrieve the antibodies and wash away everything except for the few bacteriophage that cling to them. By sequencing the DNA of those bacteriophage, they can identify which viral protein pieces were grabbed onto by antibodies in the blood sample.
That tells the scientists which viruses a person's immune system has previously encountered, either through infection or through vaccination.
The study was published in the journal Science.